Dermatology

Rhinosporidiosis

Are You Confident of the Diagnosis?

What you should be alert for in the history

Rhinosporidiosis is a chronic infection of mucous membranes, especially of nostrils and ocular conjunctiva. Involvement of the oral mucosa, skin, genitalia, urethra and anus has also been reported. The disease remains localized though disseminated lesions can sometimes occur.

Characteristic findings on physical examination

The disease manifests as polypoid or sessile masses most often in the nasal mucosa. The surface of the polypoid structures has a strawberry-like appearance due to small white spots (sporangia). The lesions are often friable. They may reach great size, obstruct the nasal passage, be secondarily infected with bacteria and become purulent. The nose is the most common site affected, particularly in the humid tropical milieu. In more arid areas ocular involvement is more common (Figure 1).

Figure 1.

Rhinosporidiosis – polypoid lesion in the right nare.

Skin lesions of rhinosporidiosis are uncommon and they are usually satellites adjacent to mucosal ones. The cutaneous lesions may be the result of autoinoculation or rarely of hematogeneous dissemination. The term dermosporidiosis has been suggested when the skin lesions predominate. Cutaneous lesions may present as warty nodules, plaques or subcutaneous swellings. Cutaneous lesions without mucosal involvement have been described. Involvement of internal organs is extremely rare.

Expected results of diagnostic studies

Histopathology: Biopsy specimens show the typical organisms of Rhinosporidium seeberi – globular cysts of varying shapes and sizes representing sporangia in different stages of development. Sporangia range from 60 to 450 micromillimetres or more in diameter and contain thousands of sporangiospores (7-15 micromillimetres). The accompanying cellular infiltrate consists of lymphocytes, neutrophils and occasional eosinophils. Neutrophils often form microabscesses. Immunohistochemistry of the infiltrate shows numerous CD8+ suppressor and cytotoxic cells while CD4+ helper cells are scanty (Figure 2).

Figure 2.

Usage of special stains is not necessary though the spherule stains with mucicarmine. Sporangia can also be seen in the material collected by fine needle aspiration.

The organism does not grow on the usual media and attempts to inoculate animals were unsuccessful. Circulating anti-rhinosporidial antibodies can be detected but they do not appear to have diagnostic significance. The diagnosis is therefore based on skin biopsy or fine needle aspiration.

Diagnosis confirmation

The typical clinical presentation of mucosal rhinosporidiosis and examination of the biopsy material allow these diseases to be excluded.

In the absence of mucosal lesions, diagnosis is more difficult and warts, verrucous tuberculosis, lipoma, cryptococcosis and pyogenic granuloma have to be considered. Vaginal and anal lesions have to be differentiated from condylomata, rectal polyps and hemorrhoids.

In parts of the world where rhinosporidiosis is not endemic, its diagnosis is made with marked delay, particularly in patients without mucosal lesions.

Who is at Risk for Developing this Disease?

Rhinosporidiosis is most often reported from southern India and Sri Lanka (90% of cases). South America is the second geographical area where rhinosporidiosis is common, in particular in northeastern Brazil and in the province of Chaco in Argentina. The two first cases of rhinosporidiosis ever reported were from Argentina.

In Africa, cases of rhinosporidiosis have been observed mainly in the central part of the continent – Rwanda, Burundi, Tanzania, Kenya, Chad and the Congo. There are several reports from South Africa. Isolated reports of cases have come from the Middle East, the USA, Cuba and southern Europe. The European patients were mainly travelers to India and Sri Lanka but autochthonous cases have been described.

Rhinosporidiosis affects mostly men. The incidence in India and Sri Lanka was highest in boys and men between the ages of 19 and 30. Since the lesions take long to manifest it is often impossible to establish age of onset.

The exact mode of transmission of the disease is not clear, although small trauma may be a predisposing factor.

Bathing in ponds and muddy waters was considered a risk factor by several authors, particularly pond bathing with animals. There have been reports in the veterinary literature of naturally occurring disease in buffalos and cattle.

Ocular rhinosporidiosis has been found more commonly in women, as reported from southern India. Ocular manifestations occurred following injuries to the eye during dust storms.

Sufferers from rhinosporidiosis are usually otherwise healthy and infection does not seem to be opportunistic.

Rhinosporidiosis has been reported in HIV-positive patients. Many patients are anemic but rhinosporidiosis is not thought to be the cause of anemia.

What is the Cause of the Disease?

Pathophysiology

Rhinosporidiosis is caused by the organism R. seeberi. The taxonomy of this agent has always been controversial. Early researchers noticed similarities between rhinosporidiosis and some aquatic parasites. Guillermo Seeber, who first described the disease in 1896, considered it a sporozoan. Later, fungal nature of rhinosporidiosis was considered. The dispute continues: a fungus or a protozoan parasite? Cyanobacterium species?

The life cycle of this organism is complex. It starts with an infecting spore penetrating the mucosal epithelium. This spore-trophocyte, 6-10 micromillimetres in diameter, grows and at 50 micromillimetres the first nuclear division occurs. Succeeding nuclear divisions follow. At 100 micromillimetres in size, a cellulose-like wall is formed.

More nuclear divisions take place until about 16,000 spores are present (spherule). The wall of the spherule becomes thinner, internal pressure leads to the rupture of its thinnest spot (pore) and spores are released into the surrounding tissue. The spores lodged in the epithelium begin the maturation process all over again.

Systemic Implications and Complications

Complications of rhinosporidiosis are rare. The intranasal lesions may reach a giant size and cause nasal obstructions, impair breathing and cause bleeding. When the lesions are located in the posterior part of the nasal cavity they may obstruct the pharynx or the larynx causing dysphagia or dysphonia. The lesions may extend to the sinuses. Assessment of the extent of involvement requires computerized tomography.

Visceral dissemination has been reported but is very uncommon. Recently, there were reports describing pulmonary involvement.

Treatment Options

Excision with electric cautery is the mainstay of treatment. The complete resection of the lesion followed by electrocoagulation of the implantation area is recommended.

Antimicrobials including antifungal agents are ineffective. Dapsone has been shown to lessen the rate of recurrence but is not considered curative. Local injections of Amphotericin B were used as an adjunct to prevent relapses and spread of the disease.

Optimal Therapeutic Approach for this Disease

Excision with electric cautery is the mainstay of treatment. The complete resection of the lesion followed by electrocoagulation of the implantation area is recommended.

Patient Management

As mentioned above, anemia does not seem to be caused by rhinosporidiosis. Recurrence can occur at any time so there is no need for regular follow up.

Unusual Clinical Scenarios to Consider in Patient Management

Cutaneous lesions without mucosal involvement have been described. Involvement of internal organs is extremely rare, but must be considered, especially in endemic areas.

Sudarshan, V, Goel, NK, Gahine, R, Krishnani, C. “Rhinosporidiosis in Raipur, Chhattisgarh: report of 462 cases”. Indian J Pathol Microbiol. vol. 50. 2007. pp. 18-21. (Rhinosporidiosis is endemic in the state of Chhattisgarh. 462 cases were seen in 12 years. Nose and nasopharynx were the commonest site (81.1%), followed by ocular lesions (14.2%). Seven cases of generalized rhinosporidiosis were seen.)

Arseculeratne, SN, Sumathipala, S, Eriyagama, NB. “Patterns of Rhinosporidiosis in Sri Lanka. Comparison with international data”. Southeast Asian J Trop Med Publ Health. vol. 41. 2010. pp. 175-191. (An analysis of 143 cases of rhinosporidiosis in Sri Lanka in 14 years. Clinicopathological and epidemiological features were compared with those in other published series. The anti-rhinosporidial IgM and IgG antibodies were assessed and found to reflect the disease of long duration.)